Upsell adds 2 pieces, checkout button has white hover

Hello,

i tried upsell popup and have 2 issues.

1)
When i add a product in upsell pop-up it gets added 2 times to my cart.
Steps to reproduce:
– Go to https://www.shopposaurus.com/produkt/personalisiertes-hundehalsband-2/
– choose an option and click ATC Button
– Upsell popup is opening
– add an item to the cart
– item gets added 2 times to the cart

2)
When i hover on checkout button in upsell pop-up it becomes totally white (is this normal?). Please tell me how to disable this hover feature in CSS.

Thanks in advance.